**It should stay in place if left undisturbed, but I would cover it in the storage area you describe.** Safe’n’Sound is a fairly firm, friction-fit mineral-wool batt; ROCKWOOL says it holds between studs without sagging. It shouldn’t simply crumble from age in a dry interior wall. [Manufacturer’s product information](https://www.rockwool.com/north-america/products/safensound/)

That doesn’t make it a durable wall surface. My practical expectation is that repeated scraping, box corners, and pressure against it would tear or compress the batts and loosen fibers. Occasional light contact is different from using it as the surface behind stored boxes.

Pegboard attached to the studs would provide useful protection. However, **for reducing furnace noise in the family room, solid drywall on both sides would perform better**: the insulation absorbs sound within the cavity, while the solid wall faces provide the sound barrier. Pegboard’s holes limit that benefit. You could leave the furnace-side drywall untaped and unpainted if appearance is your main objection.

One qualification: Safe’n’Sound itself is noncombustible, but that does **not** make an open stud wall a fire-rated separation. Before choosing pegboard, check whether your local requirements call for a particular furnace-room wall assembly, and maintain the furnace and flue clearances. ROCKWOOL’s published fire and sound ratings apply to complete assemblies that include drywall. [ROCKWOOL assembly examples](https://brandcommunity.rockwool.com/asset/_ox3bHvewz_eaPJwWxITBw/asset.pdf?quality=10)